Food for early succession birds: relationships among arthropods, shrub vegetation, and soil
During spring and early summer, shrub- and herbaceous-level vegetation provides nesting and foraging habitat for many shrub-habitat birds. We examined relationships among arthropod biomass and abundance, foliage leaf surface area and weight, vegetation ground cover, soil characteristics, relative humidity, and temperature to evaluate what factors may influence arthropod food resources for birds. Relative humidity was inversely associated with arthropod biomass; as humidity increased biomass decreased (r = -0.44, P = 0.004). We failed to detect any relationships between deciduous foliage (surface area and weight) and arthropod biomass or abundance. However, both arthropod abundance (r = 0.30, P = 0.06) and biomass (r = 0.39, P = 0.01) were positively associated with the percentage of herbaceous ground cover. Arthropod abundance also appeared to be positively associated with the percentage of clay in the soil and negatively associated with the percentage of sand. Herbaceous layer vegetation (forbs and grasses) is known to be positively associated with fire frequency suggesting a possible foraging benefit for birds during spring in habitats that are frequently burned. Management of early and late succession pine forest habitat to produce and maintain a healthy herbaceous layer will likely support more arthropods and provide quality foraging habitat for birds.